1. Field of the Invention
The present invention is generally related to marine engine cooling systems and, more specifically, to a marine engine cooling system that facilitates draining the cooling system when the engine is not operating and provides appropriate engine cooling flow paths during the engine""s operation.
2. Description of the Prior Art
Marine engine cooling systems typically utilize a pump, sometimes referred to as a seawater pump, to draw water from a body of water in which a marine vessel is operating. The water, drawn from a lake or ocean, is then used to lower the temperature of the engine and its associated components. After flowing through passages of the cooling system, the cooling water is returned to the body of water from it was drawn.
It is advisable to periodically drain the cooling water from the engine and its associated cooling passages. This is particularly beneficial if the potential exists for the cooling system to be subjected to freezing temperatures. As is well known to those skilled in the art, frozen liquid in the cooling passages of an engine and associated components can cause severe damage. Therefore, it is necessary to assure that all entrained liquid within the cooling system is drained when the marine engine is not in use and particularly if the cooling system is subjected to freezing temperatures.
U.S. Pat. No. 5,980,342, which issued to Logan et al on Nov. 9, 1999, discloses a flushing system for a marine propulsion engine. The flushing system provides a pair of check valves that are used in combination with each other. One of the check valves is attached to a hose located between the circulating pump and the thermostat housing of the engine. The other check valve is attached to a hose through which fresh water is provided. Both check valves prevent flow of water through them unless they are associated together in locking attachment. The check valve attached to the circulating pump hose of the engine directs a stream of water from the hose toward the circulating pump so that water can then flow through the circulating pump, the engine pump, the heads, the intake manifold, and the exhaust system of the engine to remove seawater residue from the internal passages and surfaces of the engine. It is not required that the engine be operated during the flushing operation.
U.S. Pat. No. 5,334,063, which issued to Inoue et al on Aug. 2, 1994, describes a cooling system for a marine propulsion engine. A number of embodiments of cooling systems for marine propulsion units are disclosed which have water cooled internal combustion engines in which the cooling jacket of the engine is at least partially positioned below the level of the water in which the water craft is operating. The described embodiments all permit draining of the engine cooling jacket when it is not being run. In some embodiments, the drain valve also controls the communication of the coolant from the body of water in which the water is operating with the engine cooling jacket. Various types of pumping arrangements are disclosed for pumping the bilge and automatic valve operation is also disclosed.
U.S. Pat. No. 6,004,175, which issued to McCoy on Dec. 21, 1999, discloses a flush valve which uses only one moving component. A ball is used to seal either a first or second inlet when the other inlet is used to cause water to flow through the valve. The valve allows fresh water to be introduced into a second inlet in order to remove residual and debris from the cooling system of the marine propulsion engine. When fresh water is introduced into a second inlet, the ball seals the first inlet and causes the fresh water to flow through the engine cooling system. When in normal use, water flows through the first inlet and seals the second inlet by causing the ball to move against a ball seat at the second inlet. Optionally, a stationary sealing device can be provided within the second inlet and a bypass channel can be provided to allow water to flow past the ball when the ball is moved against the ball seat at the first inlet. This minimal flow of water is provided to allow lubrication for the seawater pump impeller if the seawater pump is operated during the flushing operation in contradiction to recommended procedure.
U.S. Pat. No. 6,135,064, which issued to Logan et al on Oct. 24, 2000, discloses an improved drain system. The engine cooling system is provided with a manifold that is located below the lowest point of the cooling system of the engine. The manifold is connected to the cooling system of the engine, a water pump, a circulation pump, the exhaust manifolds of the engine, and a drain conduit through which all of the water can be drained from the engine.
The patents described above are hereby expressly incorporated by reference in the description of the present invention.
It is desirable that marine engine cooling systems be constructed in a way that allows for efficient passage of cooling water through heat generating components of the marine propulsion system. This includes the proper sequence in which the water flows through the various heat producing components in order to maximize the efficiency of the cooling system. It is also desirable that the cooling system can be drained with minimal human interaction when the engine is not operating. In many instances, these two goals are conflicting. It would therefore be significantly beneficial if a cooling system for a marine engine could be provided in which efficient flow of coolant is made possible when the engine is operating, and in which the various cooling passages may be easily drained when the engine is not operating.
A marine engine cooling system made in accordance with the present invention comprises a valve which has first, second, and third ports. The valve also has a cavity within it which is in fluid communication with the first, second, and third ports. A ball is disposed within the cavity of the valve. The position of the ball within the cavity is a function of forces on the ball which result from gravity buoyancy or pressure differential and from the movement of fluid through the cavity.
The marine engine cooling system of the present invention also comprises a pump having an outlet connected in fluid communication with the first port of the valve. It further comprises a fluid conducting component connected in fluid communication between the pump and the third port. This fluid conducting component can be an engine heat exchanger or one or more cooling passages of the engine itself. The ball is movable within the cavity to at least partially block fluid flow from the first port to the second port when the fluid pressure at the first port is higher than the fluid pressure at the second port. This movement causes the ball to move up and into contact with a seat associated with the second port. Fluid communication between the second and third ports remains unaffected by movement of the ball within the cavity. A fluid path from the second port to the first port remains open when fluid pressure at the first port is not greater than fluid pressure at the second port.
The cooling system of the present invention can further comprise an exhaust manifold which has a water jacket disposed in fluid communication with the second port in order to receive cooling water from the second port. The fluid conducting component of the present invention can be a heat exchanger or a cooling passage of the marine engine. The valve can be attached to an exhaust manifold of the engine. The marine engine cooling system can be a closed system, wherein water pumped from a body of water by the pump flows in thermal communication with a coolant which passes through cooling passages of the marine engine. Alternatively, the marine engine cooling system can be an open system, wherein water pumped from a body of water by the pump flows through cooling passages of the marine engine in thermal communication with the engine.
A power steering fluid cooler or other coolers can be connected in fluid communication with the pump. The third port of the valve can be connected in fluid communication with a conduit that is located between the cavity of the valve and the second port. Flow of fluid between the second and third ports is unaffected by movement of the ball within the cavity of the valve.